1. Field of the Invention
This invention is in the field of manufacturing an amorphous alloy and, more particularly, to a method of manufacturing an amorphous alloy film containing iron, cobalt, or nickel as its predominating ingredient by means of a pair of quenching rolls.
2. Description of the Prior Art
Recently, amorphous alloys have been prepared having interesting thermal, electrical, magnetic and mechanical properties. Amorphous alloys have, in general, several advantages. For one, their mechanical strength is greater than the crystalline metal materials. The modulus of rigidity is lower than that of crystalline metals by a factor of 20 to 40%. The amorphous alloys do not exhibit work hardening and their electrical resistance is generally high. The corrosion resistance of amorphous alloys can be substantially improved by the addition of chromium and the like. Finally, such alloys have been found to have high permeability.
There have been attempts made to utilize such amorphous alloys for audio recording heads, video heads, various types of transformers, delay lines and the like. There has also been some suggestion of using amorphous alloys as tensile materials and as anti-corrosive materials.
In general there are three known methods of manufacturing amorphous alloys. These are the centrifugal quenching method, the splat cooling method used with a plasma furnace, and a roll quenching method. The roll quenching method is generally inferior in cooling speed to the centrifugal quenching method and the splat cooling method. Some types of amorphous alloys cannot be manufactured by the roll quenching method, although they can be manufactured by the other methods. In the roll quenching method, an oxidation film is often formed on the surface of the amorphous alloy to provide the same with a color, and a strong amorphous alloy is hard to obtain since the cooling speed is low.
To overcome these disadvantages, it was suggested that a water bath be positioned directly under a pair of quenching rolls, and to introduce the film extruded from the rolls into the water bath. In this case, it is necessary to arrange the rolls close to the water surface of the water bath in order to introduce the film into the water bath as soon as possible. The rolls are unavoidably splashed with water when the film is led into the water bath. As a result, the width and thickness of the film are not uniform which is undesirable. On the other hand, when the rolls are moved farther from the water bath, the cooling effect is reduced and a so-called "waving" phenomenon occurs in the film extruded from the rolls. In this instance, a straight long film cannot be obtained.
To overcome these disadvantages, the assignee of the present application has suggested a novel roll quenching apparatus in Japanese Patent Application No. 22937/1977. The apparatus described comprises a pair of quenching rolls which are, for example, made of steel and are rotated in opposite directions at the same speed with the same diameter. These rolls are used in conjunction with a rotary member such as a rotary drum made of copper which is arranged adjacent to at least one of the rolls. A film or strip rolled from the rolls is guided onto the rotary member in contact with a portion of the circumferential surface of the rotary member so that it is further cooled. With the use of this type of apparatus, a strong and straight amorphous alloy film can be consistently manufactured, with little danger of oxidation.
The assignee of this application has also proposed a further novel roll quenching apparatus in Japanese Patent Application No. 22936/1977. In this application, there is described an apparatus which includes a pair of quenching rolls made, for example, of steel which are rotated at different speeds. With the use of this apparatus, a strong amorphous alloy film can be manufactured readily, with little danger of oxidation.
The apparatus described in the aforementioned Japanese applications operates very effectively, but still provides room for improvement.